The invention relates to a fault pre-warning apparatus for use in textile machines for textile webs having warp threads, in particular tufted carpets.
An apparatus for automatically stopping the winding reel of dyeing and washing machines for lengths of textile material is known from German Pat. No. 487 523. In this apparatus the winding reel includes a movable bar mounted parallel to the rotational axle thereof. The movable bar is connected to the axle of the winding reel by two inclined parallel links forming a parallelogram linkage. If the frictional drag on the spring biased movable bar increases, e.g. due to sticking of the material, the inclined links execute a circular arc movement and the end of the bar moves axially relative to the axle of the winding reel. This axial movement of the bar trips a mechanism which disengages the drive for the winding reel. The disadvantage of this known fault pre-warning apparatus is the considerable mechanical complexity and the fact that the apparatus only responds to the total tension in the web of material. Locally excessive tensions do not lead to the initiation of a switching process.
A known device for carrying out tension measurements (German laying open print No. 28 19 951) admittedly does not exhibit this disadvantage, however this device requires numerous pressure sensors which are arranged transverse to the direction of movement of the web and which are moreover journalled on ball bearings.